Print drum type matrix and sequential line printing control



May 30, 1967 J. c. SIMS, JR

PRINT DRUM TYPE MATRIX AND SEQUENTIAL LINE PRINTING CONTROL Filed June 2, 1966 789OT23456 b7890 2545 967890 3564. *567 9O 23 456789O 21 10456789O o m N R D R E M M A H SELECT HAMMERS COMPARATOR COUNTER ATT United States Patent Of 3,322,064 PRINT DRUM TYPE MATRIX AND SEQUENTIAL LINE PRINTING CONTROL John C. Sims, Jr., Sudbury, Mass., assignor to Anelex Corporation, Boston, Mass, a corporation of New Hampshire Filed June 2, 1966, Ser. No. 554,73 3 Claims. (Cl. 101-93) This invention relates to printing devices and, in particular, to a printing device wherein type faces are arranged in a matrix of rows and columns on the surface of a drum and printing of sequential lines is accomplished by the controlled operation of a row of hammers along the line being printed.

A variety of drum type printers are well known, including the devices shown in US. Patent No. 2,805,620 to Leo Rosen, Howard C. Barlow, and Ray L. Bowman, entitled, Control Means for High Speed Printing Apparatus, issused Sept. 10, 1957. In this patent, the type faces are arranged in a matrix having rows which are parallel to the axis of rotation of the drum and having columns around the periphery of the drum. Each row contains a series of identical type faces, one at each printing position (column), and different type faces are present in the different rows. The document to be printed is increment-ally moved past the drum in a direction perpendicular to the axis of rotation of th drum. A line of hammers, one for each column to be printed, is arranged on the other side of the document. The hammers are activated at the appropriate times to force the paper against the type faces to effect printing of the desired characters. Since all the type faces in any given row are identical, printing of all similar characters in a line is effected simultaneously.

The present invention is contrasted particularly in that each row of type faces contains an entire set of the characters to be printed, with a repetition of the set if there are more columns (character positions to be printed) than different characters in the set. Succeeding rows of type faces around the periphery of the drum correspond to shifted versions of preceding rows. That is, if a given row of type faces begins with the sequence 5, 6, 7 the next row of type faces begins with 6, 7, 8 The entire set of characters is represented at least once in each column of type faces. As each row of the type faces passes the line to be printed, the appropriate hammers are activated to print the desired characters.

The arrangeemnt of type faces in the present invention provides the advantage of more linearly loading the drive circuits for the hammers in ordinary operation because similar type faces are distributed in different rows on the drum. For example, in many accounting applications the character is printed more frequently than the other characters. In prior devices (where identical type faces are present in each row), the drive circuits for the hammers, and particularly the power supplies, are subjected to extremely heavy demands at the time that the row of 0 type faces passes the line to be printed. In the present invention, this demand is distributed in time as the 0 type faces occur throughout the rows of the drum.

The operation of the inventive printing device is similar to the operation of the chain or belt type printers because, at succeeding intervals of time, the type faces at the printing position are displaced from those that were at that position during the previous interval. Thus, the present invention has the advantage of permitting common logic circuits to be employed in both chain and drum printers, reducing manufacturing and inventory requirements.

It is thus a primary object of the present invention to provide a new and improved drum-type printing device.

3,322,064 Patented May 30, 1967 ice Another object is to provide a drum-type printing device wherein a set of type faces is present along each row on the drum, and wherein adjacent rows of the drum contain displaced versions of this set of type faces.

A further object of the present invention is to provide a drum-type printing device wherein a set of type faces is present along each row on the drum, and wherein adjacent rows of the drum contain similar sets of type faces that are displaced by one column along the drum.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a functional diagram of the inventive printing device.

FIG. 2 is an explanatory diagram showing a matrix of type faces on the printing drum.

In FIG. 1, a shaft 11 is continuously rotated in the direction of the arrow by a motor (not shown). The shaft supports a print drum 13 which is engraved with type faces 15 arranged in a matrix of rows and columns. A line of hammers 17, one for each column of type faces, is arranged parallel to the shaft 11. The document (not shown) to be printed is incrementally moved between the hammers 17 and the print roll 13, and one line of printing is effected between the incremental movements by operation of the hammers at appropriate times during the rotation of the print rolls. A ribbon (not shown) is arranged between the print drum and the document. While the drum is shown with forward-reading type faces for simplicity of description, in practice, the type faces are reversed to provide forward-reading printing on the document.

The surface of the print drum is shown diagrammatically in FIG. 2 as if it were out along a line parallel to the shaft 11 and flattened. As shown in FIG. 2, the type faces 15 represent the set of ten numeric characters and are arranged in a matrix of ten substantially horizontal rows and twelve vertical columns. A complete set of type faces is present in each column. Each row also contains a complete set of type faces and two additional type faces that are necessary to fill the twelve columns. Obviously, when hte number of characters in the set exceeds the number of columns, each row contains a different partial set of type faces. Although adjacent rows are shown to be shifted by one column, any shift is permissible provided that each row befins with a different type face. The type faces in each row are arranged in the same order to simplify the control circuits. The rows are skewed so that the type faces pass the line to be printed in sequence. The skew is slightly less than the width of a row.

Returning to FIG. 1, the shaft 11 also supports a binary optical code disk 19 which contains translucent and opaque regions around five circular bands. The optical code disk is illustrative of the many well-known timing devices which are suitable for use. Five beams of light are directed from a light source 21 through the bands to a five-element photosensitive device 23. The upper four beams of light intercept character-coded bands on the disk and the lower beam of light intercepts a timing band. The photo-sensitive device 23 provides binarycoded signals on four leads 25 and a timing signal on a lead 27, Where a binary 1 is provided when an opaque region is intercepted (blocking the light) and a binary 0 is provided when a translucent region is intercepted (passing the light). The code bands on the disk 19 correspond to the identity of the type faces in a particular column of the drum. As shown with the optical sensing apparatus at the bottom of the disk, the coding corre- 3 sponds to the type faces in the first (leftmost) column of the drum, and the coded signals that are generated on leads 25 correspond to the particular type face in the first column which is approaching the line of hammers. The code disk bands correspond to the order of the binary digits, with the higher orders represented by the bands of greater radius. As illustrated in FIG. 1, the

binary code 0111 (7) has just been sensed, indicating that the row of type faces beginning with 7 is passing the rows of hammers. The next code to be sensed is 1000 (8), indicative of the type face 8 which initiates the next roW of type faces to arrive at the row of hammers. In order to provide more precise operation, the coded signals on leads 25 are sampled by an AND gate 29 at the time of occurrence of the timing pulse on lead 27. As illustrated, a timing pulse occurs as the outermost beam of light interrupts the opaque region at the center of each sector of the code disk.

The signals from AND gate 29 are applied to reset a decimal counter 31 to a value indicative of the identity of the next type face in the first column to reach the row of hammers. The timing signal on lead 27 is also applied as the synchronizing (SYNC) input to a free-running oscillator 33. The oscillator produces a series of output pulses at about twelve times the frequency of the applied timing pulses so that an oscillator output pulse is provided as each type face in the skewed row approaches the row of hammers. The oscillator output signals are applied to as COUNT pulses to counter 31, thus causing the output of the counter to be successively incremented by one as the skewed row of type faces passes the row of hammers. Since the counter is reset to correspond to the identity of the first type face in the row passing the hammers as each new row approaches the hammers, and since the synchronized oscillator output increments the counter at the rate atwhich the type faces pass the hammers, the counter output is always representative of the type face which is next available for printing. This simple circuitry is usable because the sequence of type faces in each row is uniform. The type faces are preferably arranged in successive order along each row, as shown, but the circuitry can be modified to accept any order of type faces. Since the counter is reset before each row of type faces arrives at the printing position, it is not necessary that the type faces in successive rows be displaced by one column as shown. However, with the configuration shown, the circuitry can be modified to suecessively reset the counter to a number that is one greater than the number to which it had been previously reset, and thus requiring only timing pulses from the code disk. As a further modification, the SYNC signal to the oscillator or the count signal from the oscillator can be applied through an electronic delay to reduce the necessary positional accuracy of the code disk. Similarly, the various signals can be improved in shape by various wellknown circuits to permit an increase in the operating speed of the printer.

A character memory 35 is preloaded from a computer or other device with binary representations of the line of twelve characters to be printed. The memory is sequentially accessed (character by character) while its output is compared with the counter output in a comparator 37. When a match is indicated, the comparator supplies a FIRE pulse to a group of hammer drivers 39, one for each hammer 17. Accessing of the character memory 35 (by MEMORY ACCESS signals) is coordinated with conditioning of the hammer drivers (by SELECT HAMMER signals). That is, while the first character in the memory is accessed, the first hammer driver is conditioned; while the second character is accessed, the second driver is conditioned; etc. Thus, when a match is indicated by the comparator, the FIRE signal controls only the appropriate hammer. The timing for the memory and hammer drivers is controlled by a ring counter 41 which is reset as each timing pulse is received from the code disk and is stepped in position by the signals from the oscillator. The ring counter has twelve outputs, one for each character to be printed in the line. When reset, the first (uppermost) output contains a signals; after the first step, the next output contains a signal; etc. While only two output connections are shown for simplicity, the succeeding outputs similarly control succeeding memory access and hammer selection 7 circuits.

described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. A printer comprising, in combination:

a print drum having type faces arranged in a matrix having rows which are generally parallel to the axis of the drum and having columns around the periphery of the drum, at least one complete set of type faces being present in each column, wherein similar type faces in adacent rows and columns are displaced by at least one row and wherein type faces differ from their neighbors along rows;

means for rotating the drum to cause the rows of type faces to pass a printing line that is substantially parallel to the rows;

and means for providing an indication of the identity of the type face in a predetermined column which has reached a predetermined position with respect to the printing lineduring rotation of the drum;

wherein the indication providing means comprises a counter under the control of a timing signal generator which is mechanically coupled to the print drum,

the counter being incremented once for each column across each row. 2. The device described in claim 1, wherein the rows are skewed with respect to the axis of the drum.

3. The device described in claim 1, further comprising a row of controllable hammers arranged along the printing line, a multiple-character memory and a comparator, the comparator being arranged to sequentially compare different characters in the memory with successive outputs of the counter for providing hammer control signals when comparisons are indicated.

References Cited UNITED STATES PATENTS 1,405,722 2/1922 Siepmann et al. 101109 X 2,111,121 3/1938 Mills 101--110 X 2,776,618 1/ 1957 Hartley 10193 2,805,620 9/1957 Rosen et al. 101-93 2,978,977 4/1961 Eckert et al. 10193 3,085,670 4/1963 Paige 101109 X 3,128,693 4/ 1964 Thiemann 10193 3,158,090 11/1964 Wasserman 10193 3,169,473 2/1965 Irwin et al, 10193 3,207,067 9/1965 Schaller 101-93 WILLIAM B. PENN, Primary Examiner. 

1. A PRINTER COMPRISING, IN COMBUSTION: A PRINT DRUM HAVING TYPE FACES ARRANGED IN A MATRIX HAVING ROWS WHICH ARE GENERALLY PARALLEL TO THE AXIS OF THE DRUM AND HAVING COLUMNS AROUND THE PERIPHERY OF THE DRUM, AT LEAST ONE COMPLETE SET OF TYPE FACES BEING PRESENT IN EACH COLUMN, WHEREIN SIMILAR TYPE FACES IN ADACENT ROWS AND COLUMNS ARE DISPLACED BY AT LEAST ONE ROW AND WHEREIN TYPE FACES DIFFER FROM THEIR NEIGHBORS ALONG ROWS; MEANS FOR ROTATING THE DRUM TO CAUSE THE ROWS OF TYPE FACES TO PASS A PRINTING LINE THAT IS SUBSTANTIALLY PARALLEL TO THE ROWS; AND MEANS FOR PROVIDING AN INDICATION OF THE IDENTITY 